1. Field of the Invention
This invention relates to leather splitting equipment for animal hides, and especially to a hide feeding mechanism having an upper transport (gauge) roller, and a lower ring (section) roller resting on an elastic roll (rubber roll commonly used). In the following, whenever the terms pelt or hide are used, it is understood that both pelt and hide are included in the particular description.
2. Description of the Prior Art
In the leather tanning field, an important distinction exists between the upper part of the hide, which is called grain leather, and the lower part of the hide, which is called the split Splitting machines 1 are commonly used to separate these two layers (FIGS. 1 to 8B generally show known art). To achieve uniform grain thickness during splitting, the upper transport (gauge) roller 2 is set to the desired distance from the band knife 3 sharp edge. The band knife is sildingly held between an upper knife jaw 15 and a lower knife jaw 16. A ring jaw plate 17 holds ring jaw inserts 12, for scraping flesh from a ring roller 4.
To achieve successful transport of the hide, the lower feed roller 4 (or xe2x80x9cring rollerxe2x80x9d) has to have a resilient mounting and the outer periphery surface has to be capable of deviating from the straight line of its rotation axis. The ring roller 4 rests on the rubber roller 5 and has a set of rings 6 arranged on a shaft 7. The ring roller works in tandem with the gauge roller (top feed roller) to pull and spread the hide 8 towards the traveling band knife 3. A user-friendly ring roller facilitates the leather splitting process via a sturdy construction, lengthy service life, minimal downtime and minimal maintenance.
In the past, many manufacturers have made simple and xe2x80x9ceconomicalxe2x80x9d section rings 6 from various types of brass, bronze and steel material (FIGS. 2A to 2C). These friction driven section rings were assembled on a round rod or shaft 7 and kept together only with end washers 9 and adjustment nuts 10. This type of section ring was preferred by many splitters given the low overall manufacturing cost of the product. Nevertheless, this smooth, friction-driven ring roller had two apparent major drawbacks: insufficient pulling and spreading of wet and greasy lime pelts, and no means to provide a controlled gap between individual section rings.
Since slippery and greasy hides have a tendency to slide with the band knife traveling direction in lime splitting, feed roller manufacturers originally provided a 2/3 offset gauge roller corrugation 11. To further counteract this sliding effect section rings 6xe2x80x2 were notched in one direction only (FIGS. 3A to 3C). Unfortunately, this single direction style of section ring notching did not improve spreading of the lime pelt during in-feeding. The constant slide effect also caused the rings to migrate in the direction of the band knife travel. Section ring xe2x80x9clock upxe2x80x9d would occur as the individual rings became tightly grouped. These rings would xe2x80x9clock upxe2x80x9d (FIGS. 4A and 4B) when the ring roller 4 was excessively xe2x80x9ctightxe2x80x9d or when flesh was trapped between section rings 6xe2x80x2. xe2x80x9cLocked upxe2x80x9d section rings create problems during splitting, including xe2x80x9csuck-outsxe2x80x9d (an area of grain leather of extreme and uneven thickness), and xe2x80x9cwraparoundsxe2x80x9d (when flesh is trapped between section rings and pulled xe2x80x98aroundxe2x80x99 the ring roller).
To improve the pulling of wet and greasy lime pelts, manufacturers have installed a positively driven ring roller 4xe2x80x2 in lime splitting machines (FIGS. 5A to 5D). This ring roller is equipped with an xe2x80x9cX-shapedxe2x80x9d drive rod 7xe2x80x2 that ensured all rings 6xe2x80x3 turn in unison. This style of ring roller has two advantages with respect to splitting performance: even pulling of slippery and greasy limed hides, and level wear of the rubber roller. The insides of the section rings 6xe2x80x3 have to be cleaned on a regular basis to maintain their freedom of movement and rotation. Unfortunately, the xe2x80x9cXxe2x80x9d drive design has the same apparent major drawback as the original xe2x80x9ceconomicalxe2x80x9d style ring rollerxe2x80x94the lack of a controlled gap between individual section rings to counteract the constant slide effect in the band knife direction.
Lock-up of the section rings also occurs if the end nuts 10 are not properly adjusted. Two improper modes of adjustment includes: over-tightening of the assembly, restricting section ring movement, and insufficient tightening of the end nuts, causing an excessive gap between rings through which flesh could enter.
Serious problems occur with other parts of the splitting machine when section rings are xe2x80x9clocked upxe2x80x9d or do not have the proper range of motion (FIG. 6). For example, the band knife 3 may run into the ring roller 4, the ring jaw inserts 12 wear out prematurely, and the section rings 6 force uneven wear of the rubber roller 5.
In view of the preceding, it is an object of the invention to provide a hide splitting machine having a ring roller which permits hide splitting under severe conditions regarding hide wetness and greasiness, but which does not lock up the individual rings of the ring roller, nor permits any foreign substances to enter any gaps between individual rings of the ring roller.
In the invention, a hide splitting machine is provided, which comprises an in-feed table leading in to a ring roller/gauge roller combination having a traveling band knife arranged to split hides fed into a gap created between the ring roller and the gauge roller. The ring roller preferably rests on an elastic roller, for example a rubber roller. Lime pelt or wet-blue pelt is fed onto the in-feed table and onto the ring roller, which grips the pelt and transports it through the gap between the ring roller and the gauge roller. The band knife is held behind the ring roller/gauge roller, for example by an upper and a lower knife jaw, so that the hide is split into an upper grain part and a lower flesh split. Care must of course be taken to put the pelt with its flesh side down on the in-feed table. A ring jaw plate and insert is preferably arranged to scrape flesh and grease off the ring roller.
The ring roller comprises a drive shaft, a plurality of spacers and a plurality of rings (section rings). The drive shaft has a hollow center, i.e. the drive shaft is tubular in configuration. Further, the drive shaft has a plurality of axial drive bars protruding in a radial direction from the drive shaft, and a plurality of first radial holes connecting the outer surface of the drive shaft with the hollow center. The first radial holes are preferably arranged on the drive shaft between the protruding drive bars. The hollow center of the drive shaft is connected to a pressurized fluid system at one end of the drive shaft and sealed at the other end. In this way, when pressurized fluid, e.g. water or air, is fed into the drive shaft, it flows out of the drive shaft to the spacers and the rings. The ring roller assembly thus comprises individual section rings, loosely arranged on the drive shaft and cooperating with the xe2x80x9cthree prongxe2x80x9d spacers and their inner spline which, in turn, cooperates with the splined drive shaft. The rings have a substantially cylindrical outer surface, optionally having pelt gripping notches formed therein, and a smaller inside diameter. The rings have one open end and one end having an end wall (web) with a central through hole for the drive shaft to pass through. The central hole further has drive notches arranged to cooperate with teeth (prongs) arranged on the spacers, as will be described later. The drive notches are advantageously arranged in a three notch configuration. The spacers have a large diameter which is smaller than the inside diameter of a ring. The spacers further have a first end with extending gap defining teeth (prongs), a second smooth end for contact engagement with the first end of an adjacent spacer, and a middle portion between the ends, the middle portion being splined and having a diameter which is smaller than the large diameter of the spacer. When a liquid is used as the fluid, the middle portion of the spacer has a plurality of second radial holes to allow the pressurized fluid to flow from the first radial holes of the drive shaft and out to the rings via the second radial holes. All spacers are slid over the drive shaft with their respective gap defining teeth (prongs) pointing the same direction. The plurality of axial drive bars (assembly shaft splines) protruding in a radial direction from the drive shaft are arranged to be engageable with the inner spline of each spacer. Thus, a domino effect is created, as a positive drive develops through spline engagement between the drive shaft and each spacer. The gap defining teeth of a spacer are arranged to extend through the central through hole of a ring, but not interfere with the drive shaft drive bars (splines) located in the drive notches (web )of the rings when the ring roller is assembled.
Thus, when the ring roller is assembled, a ring is slid onto the drive shaft, then a spacer followed by another ring etc. The gap defining teeth of the spacers make contact with an adjacent spacer to form a gap or space allowing the end wall of a ring to move axially inside this space, thus creating a pre-defined maximum gap between two adjacent rings of an assembled ring roller. When the pressurized fluid is made to flow into the ring roller, the fluid flows from the hollow center of the drive shaft, through the first radial holes of the drive shaft, through the second holes of the spacers and further out through the calibrated gaps between the rings. The gap will thus regulate the amount of fluid which escapes the ring roller per time period.
When using a gas as the fluid, the second holes are not needed. In fact, to optimize the fluid flow in this case, the roll assembly functions better without the second holes. The fluid flows between the spacer teeth (prongs) and out between the rings, in this case.